1. Why are eclipsing binary systems important?

Select one:

a. Eclipses give information on the stars' atmospheres

b. They yield data on stellar masses and sizes

c. Evolution proceeded differently in such systems

d. They are very young stars

e. [None of the above.]

2. Suppose the mass of star X is 4 times greater than that of star Y. Both stars are main sequence stars. Which of the following is true?

Select one:

a. The luminosity of star X will be about 4 times greater than that of star Y

b. The luminosity of star X will be about 16 times greater than that of star Y

c. The luminosity of star X will be about 128 times greater than that of star Y

d. The luminosity of star Y will be about 4 times greater than that of star X

e. Luminosities cannot be predicted based on stellar masses

3. How is it possible for a very hot star to have a small absolute luminosity?

Select one:

a. It may be a very large star

b. It may be a very small star

c. Its light may be blocked by a planet

d. It may be far from Earth

e. [The question is misleading; a hot star always has a great absolute luminosity.]

4. Knowledge of which of the following allows us to calculate the mass of a binary system?

Select one:

a. The spectral classes of the stars and the distance between them

b. The distance between the stars and their period of revolution

c. The period of revolution of the stars and their absolute magnitudes

d. The absolute magnitudes of the stars and their luminosity classes

e. The luminosity classes of the stars and their spectral classes

5. Of a group of main sequence stars, the star with the greatest mass also has the

Select one:

a. greatest luminosity

b. greatest apparent magnitude

c. greatest temperature

d. [Both A and C.]

e. [Both B and C.]

6. Which of the following is true?

Select one:

a. All stars were formed at the beginning of the universe, but various stars end their lives at different times

b. Stars are formed at various times, they live out their lifetimes, and die

c. Stars are formed at various times, and once formed they will continue their lives until all stars "die" at once at the end

d. Stars are formed at various times, and they continue forever

7. Stars in an open cluster are

Select one:

a. all about the same age

b. about the same mass

c. about the same age and same mass

d. of far different ages and masses

8. _________ may trigger interstellar clouds to collapse into protostars

Select one:

a. Radiation from newly formed stars causes shock waves that

b. Radiation from supernovae causes shock waves that

c. Bursts of material from massive stars cause shock waves that

d. [Any of the above could be possible causes.]

9. Interstellar gas causes absorption lines in a star's spectrum. We can distinguish these lines from those created in the stellar atmosphere by measuring

Select one:

a. the thickness of the lines

b. the mass of the star

c. the distance from the star to the Sun

d. the size of the star

e. [None of the above.]

10. Which atom can emit or absorb radiation at a wavelength of 21.1 centimeters?

Select one:

a. Oxygen

b. Hydrogen

c. Helium

d. Neon

e. Carbon